Box furnace

ABSTRACT

A furnace comprising an outer shell in which is positioned a supporting frame and a heating unit molded of a ceramic insulating material having heating elements and mounting bands embedded therein is secured in position by the mounting bands upon the supporting frame.

United States Patent 1 1111 3,866,017

Keren et al. Feb. 11, 1975 1 1 BOX FURNACE 2,309,295 10/1957 gier, Jr13/22 x 1 Inventors William m w Mot-M10, ;?33:3.. 55/132; tiilfe'r'iiiii111......111513/333 both of Watertown, Wis. 3,350,493 10/ 1967 Randall219/407 X [73] Assignee: Sola Basic Industries, Inc., 3,500,444 3/1970Hesse et a1 219/544 Milwaukee. Wis. M 7 Primary Examiner-volodymyrMayewsky [21] A l N 449 09 2 Attorney, Agent, or FirmSmythe & Moore 52]us. Cl 219/390, 13/22, 219/407, [571 ABSTRACT 51 l Cl F27) A furnacecomprising an outer shell in which is posi- "i 25. {19/390 407 tioned asupporting frame and a heating unit molded e o are 2l9/536 of a ceramicinsulating material having heating elements and mounting bands embeddedtherein is secured in position by the mounting bands upon the sup- [56]References Cited (min frame UNITED STATES PATENTS p g 1.930336 10/1933DAmico 219/390 5 Claims, 6 Drawing Figures I E i 42 4| 2 31 i 4 t l. l li 5 H L- Q i ,l- 7%.

PATENTEDFEBI 1 I975 3.866.017

SHEET 30F 3 FIG.5

VACUUM BOX FURNACE The present invention relates to an industrialfurnace of the type having a ceramic heating unit mounted therein and,more particularly, to such a furnace wherein the ceramic heating unithas heating elements and mounting bands vacuum-molded in situ thereinand to the method of assembling such a furnace.

A furnace of the type generally used in industrial or laboratory workessentially comprises a ceramic heating unit in the general form of abox or other enclosure supported within an outer shell. The heating unitis generally made of a ceramic insulating material and may be molded.The source of energy for such furnaces is generally electricity, andaccordingly, electrical heating elements have been molded in situ in thewalls of the heating unit. The assembly or mounting of the ceramicheating unit within the shell has given rise to problems since theceramic structure of the heating unit severely limits the type offastener elements which can be used. While some form of a supportingframe is generally provided within the shell of the furnace. there isstill the problem of securely and precisely mounting the heating unitupon the frame.

It is one of the objects of this invention to provide an improvedfurnace of the type comprising a ceramic heating unit supported withinan outer shell.

Another of the objects is to provide an improved structure for mountinga ceramic heating unit within the outer shell of a furnace.

Another of the objects is to provide a simplified and effective processfor the assembly of a furnace consisting of a ceramic heating unitsupported within an outer shell.

According to one aspect of the present invention, such a furnace maycomprise an outer shell with a heating unit supporting frame beinglocated within the shell. A heating unit of ceramic insulating materialhas heating elements and mounting bands molded in situ within the wallsof the heating unit so as to be embedded therein. The heating unit ismounted upon the frame and secured in position by portions of themounting bands which protrude from the outer surface of the heatingunit.

In a method of assembling such a furnace, a heating unit is molded froma ceramic insulating material with heating elements and mounting bandsmolded in situ in the unit such that portions of the bands protrude fromthe wall of the heating unit. The unit is then secured upon a framewithin an outer shell by attaching the protruding portions of themounting band to the supporting frame.

Other objects, advantages and features of the present invention willbecome apparent from the accompanying description and drawings which aremerely exemplary.

ln the drawings:

FIG. 1 is a front elevational view of a furnace incorporating thepresent invention with portions of the front wall cut away to illustratethe mounting of the heating unit within the outer shell;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is an overall perspective view of the mounting band assemblymolded in situ within the wall of the heating unit;

FIG. 4 is an overall perspective view of the heating unit supportingframe located within the outer shell;

FIG. 5 is a vertical sectional view of a mold assembly illustrating themolding of the heating unit according to the present invention; and

FIG. 6 is a sectional view taken along the line 6--6 of HG. 5.

Proceeding next to the drawings wherein like refer ence symbols indicatethe same parts throughout the various views, a specific embodiment ofthe present invention will be described in detail.

A furnace according to the present invention is indicated generally at10 in FIGS. I and 2 and comprises an outer shell ll within which ismounted a heating unit supporting frame 12 which is illustrated ingreater detail in FIG. 4. The outer shell ll has a front wall 13 inwhich is pivotally mounted a door 14 for the heating unit and on thelower portion of which is provided with a temperature indicator l5 and acontrol and temperature regulating switch 16.

The supporting frame [2 as seen in FIG. 4 comprises a pair of parallelrods 17 and 18 having downturned portions 19 at the ends thereof whichare inserted into brackets 20 attached to the inner faces of side walls21 of the outer shell. The frame 12 also functions as a door cradle whenthe door is in the open position, and the cradle structure comprises asteel rod 22 of substantially U-shape welded to the undersides of thecross members 17 and 18 and having its closed or forward end curvedupwardly such as at 23.

Mounted within the outer shell 11 upon the supporting frame 12 is aheating unit 24 which essentially comprises a box-like enclosure havingan open face 25 which is the door or access to the heating unit. Theunit is molded of a suitable ceramic which may have fiber embeddedtherein for strength.

Embedded in the top and side walls of the heating unit are electricalheating elements which are connected to a terminal box generally locatedon the rear wall 26 of the heating unit but not shown in the drawmgs.

Embedded within the side, top, bottom, and rear walls of the heatingunit and molded in situ therewith is a mounting band assembly indicatedgenerally at 30 in FIG. 3 and comprising a transverse band 31 ofexpanded metal which encircles the top, side, and bottom walls of theheating unit. This band is embedded at a depth of about one-half inchfrom the surfaces of these heating unit walls. Attached to the sides ofthe band 31 are mounting bands 32, each of which is provided with a hookportion 33 which extends below the bottom of the heating unit as may beseen in FIG. I. The hook portions 33 are shaped to be secured around thebar 22 between the cross members 17 and 18.

A top band 34 is attached to the transverse band 3t and has a rearportion 35 which is embedded in the rear wall of the heating unit but atthe surface thereof as seen in FIG. 2.

A bottom plate of sheet metal 36 is also secured to the bottom of theband 31 and has an upwardly extending rear portion 37 which is securedto the rear portion 35 of top band 34. As may also be seen in thedrawings, and particularly in FIG. 2, the bottom band 36, 37 is alsoembedded in the corresponding walls of the heating unit but is flushwith the outer surfaces of these walls.

The forward end of band 36 is provided with an indentation 38 into whichthe lower end of a rod 40 enters when the door is open, the door beingpivoted on portion 23 of the supporting frame. The rod 40 is suitablyembedded in the door 41 of ceramic material which closes the heatingunit and pivots downwardly in the direction of the arrow 42 to theopening position as indicated by the dash lines 43. When the door is inclosed position, the lower end of rod 40 is engaged by clip 39.

The rear portion of the heating unit is supported by a rear supportbracket 44 which has its lower end secured to the outer shell and itsupper end bolted at 45 to the lower portion of rear bracket 37.

The molding of the heating unit 24 with the heating element 46 and themounting band assembly 30 being molded in situ is shown in FIGS. and 6.The heating unit is preferably molded by a vacuum molding process asknown in the art, and a vacuum applied to the inner surface of the coreto draw the slurry-containing fibers closely upon the floor to form thewalls of the heating unit. Examples of such molding re seen in copendingApplication Ser. No. 371,752, filed June 20, 1973. This process is wellknown in the art and need not be described in further detail. U.S. Pats.No. 3,500,444 and No. 3,500,464 show examples of one type of materialwhich can be employed.

As a result of this invention, the assembly of the furnace is greatlyfacilitated since the heating unit and its mounting bands are formed asa single integral unit. It is only necessary to position the heatingunit upon the supporting frame, attach the hook portions of the mountingbands to the supporting frame, and secure the rear supporting bracket.The heating unit is now precisely positioned within the outer shell ofthe furnace.

It will be understood that changes in various details of constructionand arrangement of parts may be made without departing from the spiritof the invention except as defined in the appended claims.

What is claimed is:

1. In an industrial furnace, the combination of an outer shell, afurnace heating unit supporting metal frame within said shell, and aheating unit of a ceramic insulating material having electrical heatingelements and mounting metal band means molded in situ therewith andembedded therein, said heating unit being mounted upon said frame andsecured in position by said mounting band means.

2. in an industrial furnace as claimed in claim 1 wherein said mountingband means comprises a first band and circling said heating unittransversely, a pair of hook means attached to said first band with thehook portions thereof projecting below the bottom of the heating unitand connected to said supporting frame.

3. in an industrial furnace as claimed in claim 2 wherein saidsupporting frame comprises a pair of parallel spaced rods, said hookportions connecting to said rods.

4. in an industrial furnace as claimed in claim 1 wherein said mountingband means are embedded within the wall of said heating unit aboutone-half inch below the outer surface thereof.

5. In an industrial furnace as claimed in claim 2 wherein said firstband comprises a strip of expanded metal.

* i i 4 l

1. In an industrial furnace, the combination of an outer shell, afurnace heating unit supporting metal frame within said shell, and aheating unit of a ceramic insulating material having electrical heatingelements and mounting metal band means molded in situ therewith andembedded therein, said heating unit being mounted upon said frame andsecured in position by said mounting band means.
 2. In an industrialfurnace as claimed in claim 1 wherein said mounting band means comprisesa first band and circling said heating unit transversely, a pair of hookmeans attached to said first band with the hook portions thereofprojecting below the bottom of the heating unit and connected to saidsupporting frame.
 3. In an industrial furnace as claimed in claim 2wherein said supporting frame comprises a pair of parallel spaced rods,said hook portions connecting to said rods.
 4. In an industrial furnaceas claimed in claim 1 wherein said mounting band means are embeddedwithin the wall of said heating unit about one-half inch below the outersurface thereof.
 5. In an industrial furnace as claimed in claim 2wherein said first band comprises a strip of expanded metal.